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Message-ID: <CAK8P3a2N+QW9JjOAdp3tHsXLFU3Cmy7yR3Mr3vZvi4Vy5VbOYw@mail.gmail.com>
Date: Tue, 17 Oct 2017 20:41:16 +0200
From: Arnd Bergmann <arnd@...db.de>
To: Kees Cook <keescook@...omium.org>
Cc: Mark Brown <broonie@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Subject: Re: more build problems with "Makefile: move stackprotector
availability out of Kconfig"
On Tue, Oct 17, 2017 at 8:26 PM, Kees Cook <keescook@...omium.org> wrote:
> On Tue, Oct 17, 2017 at 8:52 AM, Arnd Bergmann <arnd@...db.de> wrote:
>> On Tue, Oct 17, 2017 at 5:34 PM, Kees Cook <keescook@...omium.org> wrote:
>> index dbfb978..d5bc694 100755
>> --- a/config.guess
>> +++ b/config.guess
>> @@ -1021,7 +1021,7 @@ EOF
>> echo ${UNAME_MACHINE}-dec-linux-${LIBC}
>> exit ;;
>> x86_64:Linux:*:*)
>> - echo ${UNAME_MACHINE}-unknown-linux-${LIBC}
>> + echo ${UNAME_MACHINE}-pc-linux-${LIBC}
>> exit ;;
>> xtensa*:Linux:*:*)
>> echo ${UNAME_MACHINE}-unknown-linux-${LIBC}
>>
>> I still don't know why that makes a difference, but all versions
>> prior to gcc-6.1 have the problem for me.
>
> What happens if you add -mstack-protector-guard=tls ?
With gcc-4.8 an earlier, I get build failure:
cc1: error: unrecognized command line option "-mstack-protector-guard=tls"
With gcc-4.9 and gcc-5, I get this output:
.file ""
.text
.globl foo
.type foo, @function
foo:
pushq %rbp
movq %rsp, %rbp
subq $208, %rsp
movq __stack_chk_guard(%rip), %rax
movq %rax, -8(%rbp)
xorl %eax, %eax
movl $3, %eax
movq -8(%rbp), %rdx
xorq __stack_chk_guard(%rip), %rdx
je .L3
call __stack_chk_fail
.L3:
leave
ret
.size foo, .-foo
.ident "GCC: (GNU) 5.4.1 20170626"
.section .note.GNU-stack,"",@progbits
Arnd
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